The stabbing occurred in the 1700 block of East Eighth Street in Tempe, near McClintock and University drives. When the vehicle arrived at the address, Durazo began to stab Howato repeatedly while inside the SUV and continued the attack outside of the vehicle, police said.

Durazo then fled with the woman's 2005 Mercury SUV, which was equipped with GPS locating technology, according to Tempe police.

Responding police and paramedics found Howato with multiple stab wounds. She was in her third trimester of pregnancy. Howato and her unborn child both died, police said.

Durazo was driving west on I-10 about 22 miles from the California state line when he was located. Officers from the La Paz County Sheriff's Office and Department of Public Safety arrested him soon after, officials said.

Durazo is being held on two counts of first-degree murder, one count of vehicle theft, one count of armed robbery and one count of kidnapping, Tempe police said.

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He was initially booked into La Paz County Jail but will be transported back to Maricopa County to face charges in the woman's death, police said.

Officials for the ride-sharing company Lyft issued the following statement Monday:

"We were shocked and deeply saddened to learn of this tragedy, and our thoughts are with the family and friends of the victims,'' the company said. "The safety of the Lyft community is our top priority. The passenger's account has been permanently deactivated and we are actively assisting law enforcement with their investigation."

Police said Durazo admitted to the killing after he was arrested.

Howato was the mother of two other children, ages 2 and 4, police said.